How to make part of an object solid like a cut?
You can do this with supporting geometry. Make a loop cut Ctrl+R around the middle of the plate and slide it towards the center until it's close but not touching the center ring.

If your center section is flat like in my example, you can add a loop cut to the center of that. Then select it and bevel it using Ctrl+B to make it 2 loops that fit both the inner and outer ring.

Do this as well for the inner and outer &quot;sides&quot; of the bottom rim.

You may also need to select the center bottom face and inset it slightly. The reason this works is that Subdivision Surface and flat shading takes the &quot;average&quot; between two faces and rounds the result accordingly. The smaller the faces are, and the closer they are together (such as those clamped in by edge loops) the less area there is to round, and are therefore the edges look &quot;sharper&quot;. There are other ways of achieving this, such as selecting edges, and selecting &quot;mark sharp&quot;, however I feel it's probably best to learn how the supporting geometry works first.

Lastly, just finish it off by giving it a shiny material.